The many different species of coralline algae in the Oregon intertidal.

In a new publication just out in Global Change Biology, we tackle the question whether we can predict how marine species will respond to ocean acidification. Although many experiments have been done to show that ocean acidification will have detrimental impacts on many marine species, some species do better, while others do worse. We know little about what drives these differences. With a novel hypothesis-driven framework and using a series of field and laboratory experiments, we demonstrate that these differences in species response to ocean acidification may be overinflated.

We developed a novel framework using four main strategies derived from modern ecological theory (phylogeny, trait-based, habitat distribution, and functional identity) to assign species to groups. Similar species responses within a comparable group should greatly reduce the information required to predict global change impacts.

For example, on the left, if each line represents the measured response of a species to a global change experiment, species either (a) do not respond to global change, or (b) respond to global change. In (b), although all species are sensitive to this particular stressor, each species has a different response to it (different slope and intercept). Additional information may clarify the pattern of seeming idiosyncrasy. For example, if the different line colors in (c) represent different functional groups, species response to climate change is coherent within a group. Or, species-level traits (d) may dictate response to global change (e.g., redder lines could represent smaller species, which in this example are more vulnerable than larger species). Overall, in both (c) and (d) one might expect the same sets of species to be most vulnerable to extinction under global change, though for different reasons.

We implemented this framework to quantify the drivers of ocean acidification response in five different species of coralline algae, small "shrub-like" seaweeds that are critical species in the nearshore coastal Oregon ecosystem. We conducted a suite of studies to first assign species to different groups based on traits, evolution, and habitat, and then exposed each species to experimental ocean acidification. We found that while all species were negatively impacted by ocean acidification, all their responses were similar. This matters because if we can understand which species have similar responses to climate change (and why), that may drastically reduce the amount of information needed to predict the impact of climate change.

Coralline algae growing beneath a seagrass canopy.

This work was made possible by grants from: the Oregon State University Hatfield Marine Science Center Mamie Markham Research Award, the National Science Foundation, the US EPA, the Kingfisher Foundation, the Wayne and Gladys Valley Foundation, and the David and Lucile Packard Foundation.